PDFPLOT displays a histogram of the empirical probability density function (PDF) for the data in the input array X using nbins number of bins.
If input X is a matrix, then pdfplot(X) parses it to the vector and displays PDF of all values.
For complex input X, pdfplot(X) displays PDF of abs(X).

Example:
y = randn( 1, 1e5 );
pdfplot( y );
pdfplot( y, 100 );